WHAT’S THE DIFFERENCE between talking aloud and the voices in your head? Not much, according to your brain. Despite the social taboo, it isn’t necessarily a bad thing to hear voices in your head. In fact, we hear voices every day when we read books, mentally plan out our schedules and debate over what we should wear.
Although talking in our heads and talking out loud are noticeably different to us, our brains perceive them as basically the same action.
“The results of our study indicate that our brain does not make a fundamental distinction between the voices we hear in our head and the voice that comes out of our mouth,” says study author Thomas Whitford, an associate professor in the School of Psychology at the University of New South Wales.
How is this possible? When we speak, the brain instructs the vocal chords, tongue and lips how to move to produce the correct sounds. It also makes a copy of that instruction, what’s called an ‘efference copy’. This copy lets the brain predict what sounds it is about to hear. When our voice matches our predictions, the brain reduces its sensory response because it already knew what was going to happen.
“We found that when people produced inner speech, this was associated with an efference copy, in just the same way that overt speech is known to be associated with an efference copy,” says Associate Professor Whitford.
So, as you’re reading this article to yourself, you can ‘hear’ it thanks to the same processes that allow you to talk out loud. ■